This invention relates to a method and an apparatus for braking a rotary component of a textile fiber processing machine, such as a cylinder or roll in a bale opener, cleaner, card or rollercard unit, wherein the rotary component is associated with an electrically operable brake.
Cards or rollercard units have conventionally a main carding cylinder which, because of its substantial weight (approximately one ton) has a period of idling run in the order of magnitude of ten minutes from de-energization to stoppage. Safety considerations require that the access doors of such machine remain locked until the last rotary component is at a standstill. Particularly in case of servicing needs it is desirable that the access doors be opened as soon as possible after de-energization of the machine.
In a known apparatus as disclosed in U.S. Pat. No. 3,530,542 an electric brake 67 is coupled by an input shaft with the main cylinder of a card or is coupled by means of a belt with the principal drive motor for the carding cylinder. The braking device 67 is not coupled electrically with the main drive motor; rather, it may be energized or de-energized solely by means of contacts 204-6. Since in the known apparatus no electric connection exists between the drive motor and the braking device and only a mechanical coupling is present, this prior art braking system consists solely of an electrically operable mechanical brake. It is a disadvantage of such a system that the mechanical brake is exposed to wear and further, it has intermediate elements which have to be additionally braked, thus reducing the efficiency of the braking process. It is a further disadvantage of such a prior system that after energization of the machine the braking system can no longer be controlled.